The ABS warning light on my BMW 316ti is flashing.

Of course you need to worry until you find out what the light means . IT could be a light warning you of a possible serious fault in the engine/ transmission ( engine fault light from no water ,brakes etc ) have it checked out before it can become costly.. Lights are not there as Christmas decorations but to save you money.

transmisson replacement is necessary.
thanks.

any one of the abs sensor could be faulty, have it scanned for fault codes to be sure.

It may be overdue for a scheduled tune-up, oil change, etc.

The vehicle owner's manual will contain that information.

BMW MODELS AFFECTED: All with ABS

FAULT: ABS warning light comes on intermittently. Normal troubleshooting procedures find no defect.

Possible Cause: If car has recently had two new tires, or snow tires put on. Sometimes when the car is driven over 50 MPH.

Solution: Check all four tires on the car, make sure they are the same brand, style, and size. Check if
any of the new tires have substantially more tread than the rest. These differences may cause enough
variance in rolling diameters to confuse the ABS control unit, which in turn, gives a false signal to the ABS
warning light.

If that is not the issue, it is most likely the ABS control module failing.

ABS/ASC module is faulty
CLASSIC ABS FAILURE SYMPTOMS:
- Most of the time, the problem is the ABS module or one of the 4 wheel speed sensors (& sometimes the brake pressure sensor)
- In my 2002 BMW E39 DSC, three orange (warning) cluster display lights lit, ABS, Brake, & DSC
- The 3 warning lights reset when the ignition is turned off, only to repeatedly reappear within minutes of normal driving
- The fault is often intermittent leading you to falsely believe you've resolved the problem (proper diagnosis is important)
- Sometimes the fault only appears when the engine is hot; other times only at speeds over 40 mph
- Carsoft may erroneously show a rear speed sensor failure; but just replacing the speed sensor may make no difference.
- All the work is in correct diagnosis of the problem; parts replacement is trivial (from 1 to six bolts in a few minutes)
- Hence, this BMW E39 ABS 3-warning light DIY will concentrate on understanding and diagnosis of the problem

Sounds like a bad ABS control module is at least part of your problem. The symptoms are usually and ABS and TRACS light intermittent or constand and eventually your speedometer works intermittently or totally quits. This guy rebuilds/upgrades them for about $140. New ones run over $800. http://home.earthlink.net/~vicrocha/Volvo_Parts/Volvo_ABS_removal.htm

Bad ABS control module. This guy rebuilds them: http://home.earthlink.net/~vicrocha/Volvo_Parts/Volvo_ABS_removal.htm

The ABS control unit does need to be coded to the vehicle. After coding the control unit, an End-Belt run test must be performed. I know that you will also have transmission faults stored, because the Trans warning is set since the control unit has not been coded
and the control units communicate constantly during engine operation. The trans uses abs input for shift characteristics and helps with power reduction during evasive driving control. A dealer should be able to code and perform the end run test and usually charge about an 1hr fee. They will also need to quick delete other fault memories.